Mechanically instructive biomaterials: a synergy of mechanics, materials and biology
Zhenwei Ma, Jianyu Li
Department of Mechanical Engineering, McGill University, Montreal, Canada
dear Friends and Colleagues
I have been invited to write a review, actually a "Perspective" paper on Contact Mechanics from my personal point of view, which obviously reflects my own experience in my nearly 30 years of research activities. This is a sort of "celebration" therefore, and I would like to make it as simple, complete, and elegant and useful as possible.
Any comment therefore on this preprint would be greatly appreciated.
https://www.researchgate.net/publication/415644414
Film-substrate systems are prevalent in various industries, and manipulation of their adhesion strength is essential to guarantee their desired functionalities. Inspired by the heterogeneous characteristic of geckos’ spatulae, heterogeneous adhesion devices are proposed for enhanced directional adhesion, but experimental measurements of their adhesion strength are significantly lower than the theoretical predictions. This discrepancy is likely due to the cohesive zone, a factor that was usually overlooked in previous theoretical models.
A compliantly fixed hemispherical indenter in adhesive contact with an elastic sample firmly bonded to a rigid base is considered under the assumption that the rigid base undergoes small-amplitude high-frequency normal (vertical) oscillations. A general law of the rate-dependent JKR-type adhesion is assumed, which relates the work of adhesion to the contact front velocity. Using the Bogoliubov averaging approach in combination with the method of harmonic balance, the leading-order asymptotic model is constructed for steady-state vibrations.
In unidirectional sliding of rubber contacts on smooth hard surface it has been found that contact shrinks largely in longitudinal directions, and generally much less in the transverse direction, and two explanations have been suggested to explain this: one is the effect of mixed mode fracture mechanics in the presence of adhesion (with mode II reducing adhesion and mode III less clear), and another uniquely based on finite strain effects even for a simple material model as neo-Hookean hyperelastic material.
Considerable research has been conducted on shape of pillar ends for optimal adhesion. In experiments with elastomers it has been found that mushrooms-ended ones are superior to flat-ended ones, but early experiments have suggested an extremely strong scaling in strength with pillar radius (del Campo et al Langmuir;23 :10235-43, 2007). We discuss various theories and experimental results on scaling of strength, and in particular we elaborate recent experiments on single pillars with mushroom ends finding that the scaling on strength is much less surprising.
We are hiring 2 post-docs soon in Italy at the Department of Mechanics DMMM of the Politecnico di BARI. The subject is here described.
The Gordon Research Conference on the Science of Adhesion is this summer (23-28 July 2023). The meeting will be held on the campus of Mount Holyoke College in western Massachusetts and will have more than 20 invited talks from world leaders in the fields of adhesion, soft matter, and materials. This is a great meeting for students and early career researchers to get connected to the community. Poster presentations are strongly encouraged from all participants, and poster abstracts can still be submitted.
